Bulked bonded yarn

ABSTRACT

DEVELOPED BULK IS IMPARTED TO A YARN COMPOSED OF SIMILAR CONDINUOUS FILAMENTS. ADJACENT BULKED FILAMENTS ARE THEN BONDED AT POINTS WHERE THEY CONTACT ONE ANOTHER. THE BULKED BONDED YARN IS PARTICULARLY SUITABLE FOR USE AS TYING TWINE AND SIMILAR APPLICATIONS DUE TO ITS IMPROVED KNOT HOLDING ABILITY, BUNDLE COHESION, AND HIGH STRENGTH.

LL J.,PONSQO N 3,553,953 i ['BULKED 130mm YARN 'Jah.-12,

Ffld Sept. 5, 1968 INVENTOR- LLOYD J PONSDN WOC I ATT on; EY

United. States Patent 3,553,953 BULKED BONDED YARN Lloyd J. Ponson, Gulf Breeze, Fla., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware Filed Sept. 3, 1968, Ser. No. 756,790 Int. Cl. D02g 3/00, 3/40; D02j 1/12 U.S. Cl. 57-140 3 Claims ABSTRACT OF DISCLOSURE The invention relates to the production of a novel bulked bonded yarn formed from continuous filaments, and to a process for producing such yarn.

Continuous filamenttire and industrial yarns have a number of properties desirable for such end uses as tying twine and the like. However, such yarns as usually produced lack knot holding ability, bundle cohesion, and bulk as compared to twine formed from staple fibers such as cotton. For example, the ordinary overhand knot as tied by commercial knot-tying machines will slip at a tension well below the tension required to break the yarn when using tire yarn, but will not slip with cotton twine. These disadvantages outweigh the normal continuous filament advantages of high strength, resistance to rotting, etc.

According to the present invention, continuous filament yarns are modified to increase knot holding ability and bundle cohesion, resulting in a product particularly adapted for use as a tying twine.

Accordingly, a primary object of the invention is to provide a continuous filament yarn having bonded bulk.

A further object is to provide a continuous filament yarn of the above character in which the yarn has superior knot holding ability.

A further object is to provide processes for producing yarns of the above character.

For a more complete understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accompanying drawing, in which:

FIG. 1 is a schematic perspective view of preferred apparatus for producing yarn according to the invention;

FIG. 2 is an enlarged view of yarn according to the invention; and

FIG. 3 is a perspective view of an alternative yarn takeup mechanism-for imparting twist to the yarn.

Referring generally to FIG. 1, yarn 20 is fed from supply means 22 to a bulking region 24 wherein developed bulk is imparted to the yarn. The bulked yarn is next fed to bonding region 26 where the filaments are bonded in the bulked condition to adjacent filaments at points where they contact each other. The bulked bonded yarn is collected in an orderly fashion as by the schematically illustrated yarn takeup mechanism 28.

Referring more specifically to FIG. 1, supply means 22 can include more than one supply package 30, with individual threadlines 32 being fed through suitable guides 34 and plied or combined to form yarn 20.

The preferred bulking region 24 includes a pair of driven feed nip rolls 36 for forwarding yarn 20 at a given speed to the upper end of bulking chamber 38. Chamber 38 may be of the type disclosed in U.S. Pat. 3,303,508, to Hills et a1., if yarn 20 has latent bulk which can be developed by heated fiuid impinged on the yarn passing through chamber 38. Suitable methods for imparting latent bulk are disclosed, for example, in U.S. Pat. 3,024,517 and 3,092,890, both to Bromley et al. Yarn 20 is withdrawn from the opposite end of chamber 38 by a second pair of nip rolls 40 driven at a lower speed than rolls 36. The relative speeds of rolls 36 and 40 control the degree of bulk, as disclosed in U.S. Pat. 3,303,508.

The bulked yarn 20 leaving rolls 40* passes to bonding region 26, wherein the individually bulked filaments are bonded together at the points where they contact one another. In the illustrated apparatus, bulked yarn 20 contacts the periphery of a slowly rotating applicator wheel 42, the lower portion of which rotates in container 44 of adhesive dissolved in a volatile solvent. When yarn 20 is Nylon 66, the adhesive advantageously is a polyamide resin, although other types of adhesive can be used successfully. A suitable example of such an adhesive can be prepared by dissolving 15 parts by weight of polyamide resin in 85 parts of a volatile solvent. The preferred resin is commercially available as Emery 3792R, available from Emery Industries, Inc., Cincinnati, Ohio, and a suitable solvent for this resin is a mixture of equal volumes of n-butanol and toluene.

The speed of rotation of wheel 42 is selected to control the amount of adhesive applied per unit length yarn. Generally, this will be within the range of 0.001 to 3% adhesive based on the weight of yarn leaving nip rolls 40. The preferred level of adhesive on the dried yarn using the aboveidentified commercially available polyamide resin is about 0.5%.

After contacting the periphery of applicator wheel 42, yarn 20 proceeds downwardly under idler roll 46 before being wound without twist on the bobbin in takeup mechanism 28. One purpose of idler roll 46 in the particular illustrated apparatus is to increase the time interval between application of the adhesive and winding. This permits most of the solvent to evaporate before the yarn is wound in the package, so that adjacent wraps of yarn on the package will not adhere together. This function of roll 46 could be eliminated if the direct distance between wheel 42 and the bobbin were suflicient to permit evaporation of the solvent. If necessary, a heater could be added between wheel 42 and the bobbin to assist in drying the yarn before winding. It should be understood that other means for applying the adhesive could be used as an alternative to the rotating wheel 42, for example by wicking.

The tension on the yarn While the adhesive is being applied and dried or otherwise set should be low enough that the desired bulk level is maintained, and can readily be selected by one skilled in the art. One means of controlling tension would be to permit roll 46 to yield or rise with increased tension, although a number of other means for controlling tension are known in the art and can be used.

The preferred yarn has the general appearance illustrated in FIG. 2, wherein the crimp or bulk of the individual filaments is generally sinusoidal, with convolutions of adjacent filaments being out of phase. Particularly when the yarn is to be used as a tying twine, the degree of bulk should be within given limits. The bulk in a given yarn can be determined by dividing the measured yarn denier by the calculated denier. The calculated denier is derived from the sum A of the measured cross sectional areas of the several filaments, expressed in cm. and the density D of the filamentary material, expressed in grams/ cc. The calculated denier is equal to 9X10 AD, and is the denier the yarn would have if all filaments were straight rather than bulked. The measured denier is determined by A.S.T.M. test method Dl907-61T. To have acceptable knot-holding properties, the ratio of measured denier to calculated denier should be at least 1.03, while the yarn would generally be too extensible for this end use if the ratio were greater than about 1.20. Preferably, the ratio is between 1.06 and 1.15 if the yarn is to be used as a twine. Ratios greater than 1.20, however, are useful for other end uses, such as for a knitting or weaving yarn, or for carpet pile.

While the feed yarn preferably contains latent bulk according to the Bromley et al. patents noted above, with the latent bulk being developed in a chamber of the type disclosed in the Hills et a1. patent noted above, other known methods for bulking the yarn may be used. Thus, the yarn to be fed to bonding region 26 may be bulked by being drawn over a sharp edge, by stutter box crimping, by false twisting and heat setting, or by subjecting drawn yarn to turbulent fluid by processes similar to those disclosed in US. Pats. 2,783,609 and 3,005,251. A further useful type of yarn is the conjugate-spun type wherein the spun filaments include two components having different shrinkage properties within the same filament. Another useful known yarn is bulked by applying a temperature gradient across the filaments. However bulked yarns wherein some filaments are shorter than others are not suitable for use in the present invention, since the longer filaments would not properly share an applied load. Such an undesirable yarn could be made by bulking yarn composed of filaments having different shrinkages so that some filaments in the final bonded yarn would be shorter than others and consequently be less textured or bulked. Thus, a requirement of the present invention is that substantially all filaments be similar, that is, have substantially the same lengths over a reasonable bonded yarn sample length such as ten yards, and therefore all filaments will be equally textured or bulked.

The bulked, bonded yarn according to the invention can be used directly as tying twine or for other purposes, 1

although it is generally desirable to add a small amount of twist when it is to be used as tying twine. Between /2 and 2 turns per inch twist is usually satisfactory, although up to 10 or more turns per inch could be added for particular end uses. The twist can be added immediately after the bulk has been bonded or in a later separate operation. When the twist is added immediately after the bulk has been bonded, the yarn takeup 28 illustrated in FIG. 1 as a winder mechanism can be replaced by the conventional ring-and-traveller assembly shown in FIG. 3.

When the bulked bonded yarn is intended for use as a tying twine, it is particularly desirable that the tenacity be at least 6 grams per calculated denier. The measured denier should be at least 400 for most efiicient use with commercial knot-tying machines, since smaller yarns are diflicult to handle and would not have adequate strength.

What is claimed is:

1. Ayarn comprising:

(A) A plurality of continuous filaments having sufficient developed bulk that said yarn has a ratio of measured to calculated denier of at least 1.03;

(B) Adjacent filaments being bonded together at points of contact with one another;

(C) Substantially all individual filaments in a 10-yard length of said yarn having substantially the same lengths;and

(D) Said yarn having a total measured denier of at least 400 and a tenacity of at least 6 grams per calculated denier.

2. The yarn defined in claim 1 wherein said yarn is twisted to a level of between /2 and 10 turns per inch.

3. The yarn defined in claim 1 wherein the ratio of measured to calculated denier is within the range of 1.06 to 1.20.

References Cited UNITED STATES PATENTS 2,807,864 10/1957 Head 57153 3,099,594 7/1963 Caines et a1. 2875X 3,142,147 7/1964 Betsch 5714O 3,186,155 6/1965 Breen et a1. 161-177X 3,251,181 5/1966 Breen et al. 57-14O 3,262,181 7/1966 Hawkins et a1. 281.4X 3,448,500 6/1969 Benson 28-72.12

DONALD E. WATKINS, Primary Examiner US. Cl. X.R. 

